Within integrated circuits, semiconductor devices such as memory cells including their components are becoming smaller. The smaller components are needed in a memory cell such as those in a static-random-access memory (SRAM). As the size of a SRAM cell decreases, the operational speed of the SRAM typically increases, the power consumption typically decreases, and yields generally increase. Still, the smaller SRAM cell has its problems. The amount of charge at a storage node is about the product of the capacitance of the storage node and the voltage difference between the plates of the storage node capacitor. The smaller SRAM cell typically has less capacitance because the area of the storage node capacitor typically decreases with the SRAM cell size. The decrease in capacitance may allow alpha particles to cause soft errors.
Incorporating additional capacitors within a SRAM cell is one way to increase the storage node capacitance, which typically reduces the soft error rate of the SRAM cell. Capacitors that are connected to the storage nodes are discussed in many patents and technical articles. A dynamic-random-access memory (DRAM) typically has a storage capacitor such as a fin capacitor. Many DRAM storage capacitors including fin capacitors are complex and would require many additional processing steps to an existing SRAM process. In another attempt to reduce soft error rates, a SRAM cell may have its storage nodes capacitively coupled a relatively constant voltage supply such as V.sub.SS, V.sub.DD, or a fraction of V.sub.DD. The capacitor plates, which are connected to the relatively constant voltage, may need additional contact openings or a specialized interconnecting layer in addition to the layer used to form one of the plates of the capacitor.